Yesterday, Feb. 26, was the 40th anniversary of the tragic Buffalo Creek coal sludge (also known as “slurry”) dam failure that killed 126 people and left thousands injured and homeless.

What is sludge? Before coal can be sold, it has to be processed. During the processing of coal, it’s washed in a chemical mixture to remove the dirt, rocks and clay. The resulting waste is a toxic brew of carcinogenic materials, chemicals and heavy metals that coal companies store in massive earthen dams near where they mine the coal. Coal companies dig out entire lakes to fill with this nasty stuff, and it just sits there either in perpetuity or until the dam breaks and explodes onto the communities below. Sludge dams pose a particularly looming danger in Appalachia, where they are built high up in the mountains, in perfect positioning to bring a black wave of death down to the towns and communities below them.

This is what happened in Buffalo Creek, West Virginia in 1972. Heavy rains came during that fateful week in late February, stressing the already weakly constructed sludge dams of the Pittston Coal Company.

Once the first dam broke, it only took a few minutes for the tidal wave of toxic sludge to take the lives of 126 people, injure 1,100, and destroy the homes of 4,000 more.

Whole communities saw the lives of their loved ones and their homes snuffed out. Their families, their communities, their health were destroyed. Their sense of security was ripped away with the flood; healing would take decades.

For a detailed account and explanation of the disaster, watch this video.

Today, sludge dams continue to be a grave threat to the people of Appalachia – one could argue the threat today is even more alarming. The expansion of mountaintop removal mining has made way for much more enormous and many more sludge dams. With all of its mountaintop removal mining, West Virginia alone has 110 dams. Many can store more than 100 billion gallons of sludge. See recent photos of a massive sludge dam from a mountaintop removal mining flyover.

One of the most significant things we can do to reduce the danger of these sludge dams is stop mountaintop removal mining. While stopping mountaintop removal mining won’t eliminate these dams, it would significantly reduce their proliferation and threat.

And of course, it is critical that we never forget Buffalo Creek and continue to raise awareness of the danger of these sludge dams. Earthjustice’s close partners, the Ohio Valley Environmental Coalition and Coal River Mountain Watch, have been working together since 2004 to improve the health and safety of residents living in the vicinity of coal sludge dams. Their Sludge Safety Project has made significant gains in protecting communities and bringing attention to the dangers of toxic coal sludge.